1. Field of the Invention
The present invention relates generally to piezoelectric composite transducer assemblies, and more particularly to a piezoelectric composite transducer assembly that can be shaped into a complex curved configuration.
2. Description of the Prior Art
Transducer assemblies are frequently mounted on a supporting structure which currently must be a flat or simply curved surface. These situations can be handled by one-dimensionally curved transducers made from either injection molded 1-3 piezocomposites or flex circuits with composite conductive/nonconductive adhesive films. However, in many underwater acoustic applications, it is desirable to have a transducer assembly conform to a structure that presents a more complex curved surface. For example, most underwater vehicles are curved in one direction across the bow and curved in another direction from bow to stern. If the same transducer assembly must conform to both of these curves, the only option is to design and laminate a contour specific flex circuit to adhesive film components. Alternatively, flat sensors may be attached in piecewise fashion to approximate a curved surface. Unfortunately, these assemblies are very expensive to design and fabricate.
Accordingly, it is an object of the present invention to provide a transducer assembly and method for making same that can be shaped to conform to complex curves.
Another object of the present invention is to provide a transducer assembly and method for making same that is cost effective.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a piezoelectric composite transducer array and method for making same are disclosed. A block of piezoelectric material has a common base and a plurality of uniform-length rods extending from the common base in a parallel and regularly spaced-apart fashion. A first surface region is defined at outboard ends of the rods and a side region is defined about the periphery of the array. At least one electric conductor is positioned to extend through the side region and substantially parallel to the rods such that the electric conductor(s) extends at least to the first surface region. If the array is to be shaped, the electric conductors are located approximately at the midplane thereof. Spaces between the rods are filled up to the first surface region with a viscoelastic material. The common base of the block is then removed such that a second surface region parallel and opposite to the first surface region is defined. At least one electrode is deposited at the first surface region to be in contact with at least a portion of the rods and in electrical contact with the electric conductor. At least one ground electrode is deposited at the second surface region to be in contact with the rods. As a result, a piezoelectric composite transducer is formed. If a thermoplastic material is used for the viscoelastic fill material, the piezoelectric composite transducer can be shaped by heating the thermoplastic material to its plastic state.